palindrome-fun.js

// Just a fun experiment at testing palindromes by division

// test if a string is a palindrome by dividing length of string and looking at left and right
function isPalindromeByDivision(str) {
  if (!str) {
    return;
  }

  let result;
  // clean up string - remove spaces and enforce casing
  let cleanedString = str.replace(/\s/g, '').toLowerCase();

  // find middle
  // Note: that by using floor we will get the min of whole length
  // so if there are odd amount of characters the very middle character will not be read
  // which is correct in cases like `alula` we want to ignore the `u`
  var middle = Math.floor(cleanedString.length / 2);

  // store left hand side of string up to middle
  let leftStr = cleanedString.slice(0, middle)
  // get right hand side of string and reverse, then join back to string
  let rightStrReversed = cleanedString.slice('-' + middle).split('').reverse().join('');

  // is a palindrome if left and right string are the same
  return leftStr === rightStrReversed;
}

let phrase = 'A nut for a jar of tuna';
let isPalindrome = isPalindromeByDivision(phrase)
console.log(`${phrase} is a palindrome: ${isPalindrome}`)